1. Field of the Invention
Core-flow represents the pumping through a pipeline of a viscous liquid such as oil or oil emulsion, in a core surrounded by a lighter viscosity liquid, such as water, at essentially the pressure drop of the light viscosity liquid. Normally, core-flow is established by injecting the water by separate means around the viscous oil being pumped in a pipeline. The present invention involves the establishing of core-flow of less viscous liquid in viscous liquid emulsions or dispersions by creating a certain shear rate for a certain length of time in a pipe flow to break the emulsion and create a less viscous liquid rich zone near the pipe wall. Any light viscosity liquid vehicle such as water, petroleum and its distillates may be employed. Any high viscosity liquid such as petroleum and its by-products and mixtures thereof including solid components such as wax and foreign solids such as coal or concentrates, etc. are also useful.
2. Description of the Prior Art
Crude oil as it is normally produced in oil fields contains some water. Before such crude oil is pipeline transported, it is desirable that it be freed of the water. This is not difficult where the oil-water mixture contains only free water which will separate easily from the oil by merely providing a vessel in which water-oil phase separation occurs through the difference in gravities of the water and the oil. Where the water is dispersed through the oil in small particles, the separation is much more difficult. This mixture of water-in-oil may be referred to as either an emulsion or a dispersion and is highly difficult to separate into water and oil phases inasmuch as the minute particles of water are dispersed in the oil in a very stable condition. Stability exists due to the extensive area of interface between the oil and water in the emulsion.
To break emulsions in which water is dispersed in oil requires coalescing the particles of water into larger droplets which can then settle out due to gravity or be separated through other effects. This is accomplished by both physical and chemical methods which may involve the application of heat or electricity. All of the various methods proposed in the art and employed commercially for breaking emulsions and recovering the oil essentially free of the water suffer from various short comings. Among these are the incomplete separation of the oil and water and the high cost of the separation techniques which usually require several steps.
The present invention not only provides a technique which is simple for separating oil and water, as well as other viscous and less viscous liquids, but utilizes the water or other less viscous liquid once it has been separated, for transportation of the oil or other viscous liquid by a vastly improved technique which more than offsets the cost of the separation. The solution of the present invention to the problems of the prior art will become more apparent from the following description thereof.